Photographic lens



(No Model.)

W/QLOZ@ (op. fmfe.

SR n Wl-..1

WMV

fn xl v NHA Y Y J C. H. E. KROGMANN. PHOTOGRAPHIG LENS.

Patented Aug. 27, 1889. Il 2.67

lay]

ATTORNEYS.

N PE ms. Pnmumnugnpnw. wnhmym u. c.

UNITED STATES CHARLES H. E. KOGMANN, OF CINCINNATI, OHIO.

PHOTOGRAPHIC LENS.

SPECIFICATION forming part of Letters Patent N 0. 409,981, dated August 27, 1889;

Y Application filed January 7, 1889. Serial No. 295,896- (No model.)

To a/ZZ whom it may concern.-

Be it known that I, CHARLES H. E. KEoG- S MANN, of Cincinnati, in the county of Hamp. the following is aspecifcation, reference beingl ."of the same.

- i5.' The objectof my ilton and State of Ohio, have invented a new and Improved Photographic Lens, of which had to the annexed thereof, in which- Figure l is a longitudinal section of a photographic-lens tube constructed according to my improvement, and Fig. 2 is a modification drawings, forming a part Similar letters of reference indicate correspending parts in both views.

invention is to construct a photographic l'ens in which the intensity of the light' will be equal throughout the entire field and ,in Which the sharpness/of the image will be uniform, and one which may be used for both portraits and views and which may be adapted for telescopic,- microscopic, and

other uses where an achromatic objective is required. i

The invention consists inthe peculiar construction and arrangement of parts, as hereinafter fully described, and pointed out in the claim.

In carrying out. my invention I provide an achromatic lens A, formed of. a double conand a meniscus concave lens b, of

Vex lens a PATENT OFFICE.

dint-glass, the two lenses being connected together in the usual Way. The achromatie lenigis arranged in the rear end of the tube B. Iii' the front of the said tube Bis placed a singlifr" menis'cus concave lens C, of ,crown-g1asS,-au5l-f 35 between the lens C and lens A is arranged@l diaphragm D, which screens off some of the# marginal rays 4 In Fig. 2 the construction is substantiallyff Y 1, the same, exdept that the `front lens C. is a ad single plano-concave lens of crown-glass, of smaller diameter than the lens C, and the diaphragm D', having a smaller aperture than that of the diaphragm D, is arranged near the front lens C. This -construction enables 45 me to use a shorter tube B.

Having thus described my invention, I claim as new and desire to secure byLetters Patent- In a lens for photographic and other purposes, the combination of two unequal lenses, the front lens being asingle concave lens with negative focus, and theback lens an achromatic lens with positive focus, the two focuses or powers being separated by a diaphragm,-` substantially as specified. 

